There are so many variables to consider - your lifestyle (casual/dressy), your interests, whether you want more of a mix of Europeans & Americans or not, size of the ship (which can affect which ports it can visit), etc. Have you cruised before? If so, how recently, which cruise line, and how did you like it? (And what did you like or not like about it?) If you can help us out with more information, we can probably advise you better. There is no one single "best" cruise line.